The present invention relates to electro-acoustic transducers, and especially to such transducers for use in loudspeakers. The invention particularly relates to dome-shaped transducers, for example high frequency transducers commonly referred to as “tweeters”.
Rigid (“hard”) dome-shaped electro-acoustic transducers arranged to radiate high frequency acoustic waves (for example above about 15 kHz) have been used in loudspeakers for many years. It is fundamental to their ideal functioning that such hard dome-shaped transducers are substantially rigid (such that they exhibit minimal flexing during use) and have a low mass (such that the maximum proportion of input power is converted to acoustic output power). These twin objectives have hitherto been achieved by a combination of the inherent structural rigidity of the dome shape, and the use of low density materials, including plastics materials, low density metals and metal alloys, ceramics and composite materials.
Specific examples of the huge number of known dome-shaped electro-acoustic transducers include those disclosed by U.S. Pat. Nos. 4,531,608 and 6,757,404 B2, among many others.